Suppressing coking on surfaces



Patented Nov. 18, 1941 surrasssmo ooxme N summons Edward B. Peck, Elizabeth, and Peter J. Gaylor,

Union; N. J assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application June 24, 1939,

Serial No. 281,052

2 Claims.

Thisinvention deals with a method for inhibiting or retarding the formation of coke and tarry matter upon heated surfaces in contact with organic materials.

Coking and carbonization difllculties have been encountered in industrial equipment such as cracking coils, vacuum distillation towers, combustion chambers of automotive engines, heat transfer equipment and the like. An object of the present invention is to retard or eliminate such coking or deposition of tarry materials which hinder and interfere with the operation of the equipmentemployed for commercial uses.

The present invention involves the coating of the surface in contact with the organic substance with a layer comprising zinc oxide. A large number of elements and compounds have been tried,

possible to obtain a homogeneous adherent coating of zinc oxide which will withstand vibration and mechanical handling without loss of the protective coating.

Such coatings may be applied to the metallic or other surfaces which have a tendency to coke or collect tarry deposits. Ferrous and nickel surfaces are especially noted for their coke-collecting tendencies. 1

Zinc oxide also tends to suppress the cracking of organic compounds, and in this respect it is valuable where cracking is to be avoided. Hence, it may be employed as a coating or ingredient for a catalyst employed in thermal reactions such as cracking, dehydrogenation, reforming, isomerization, polymerization, etc. Zinc compounds readbut it has been found that only zinc oxide ex 7 hibits a strong enough inhibiting effect agains;

coking to justify its commercial use. Although "it is possible to coat surfaces with zinc oxide by the use of paints, varnishes or lacquers. containing at least or preferably 50% or more zinc presence of air or oxygen for a limited length of time. The second method involves the treatment of the metal surface with zinc vapors in presence of reducing gases for such a period of time as to allow the zinc to penetrate into the metal to such an extent as to form a bonded surface, after which oxidation of the zinc surface is carried out as set forth above.

face orspraying the surface with the molten metal inv a reducing atmosphere followed by the The third method consists in galvanizing the metallic suring hydrocarbons.

oxidation procedure. With these processes, it is ily convertible into zinc oxide on oxidation may also be employed dissolved or dispersed in lubricants and fuels so as to prevent deposition of "made substantially free of carbon be coated with zinc oxide to obtain the best results.

We claim:

l. A method of thermally cracking hydrocarbons to produce gasoline in a reaction container made of metal containing iron and nickel which have coke forming characteristics, which comprises coating the'-internal surface of said metal reaction container with a homogeneous adherent protective coating of zinc oxide and then heating hydrocarbons in said reaction container having an internal zinc oxide coating to a cracking temperature for a sufficient time to effect the desired extent of cracking. I ,2. A method according to claim 1 wherein the .zinc is deposited as a thin film of metal on the internal surface of said reaction container and then is oxidized to form an adherent layer of zinc oxide before said container is used for crack- EDWARD B. PECK.

PETER J. GAYLOR. 

